Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$62.33	10.788%	$69.0542	$69.05	$69.05	$69.10
Purchase #2	$217.25	7.395%	$233.3156	$233.32	$233.30	$233.30
Purchase #3	$76.98	6.655%	$82.103	$82.10	$82.10	$82.10
Purchase #4	$237.33	13.305%	$268.9068	$268.91	$268.90	$268.90
Purchase #5	$187.99	12.856%	$212.158	$212.16	$212.15	$212.20
Purchase #6	$80.31	6.233%	$85.3157	$85.32	$85.30	$85.30
Purchase #7	$109.94	13.636%	$124.9314	$124.93	$124.95	$124.90
7 purchase totals =	$972.13		$1,075.7847	$1,075.79	$1,075.75	$1,075.80